in later analysis – all crucial tools in the study of animal behavior
(Altmann, 1974). Second, the activity emphasizes the discussion of
issues that can arise from external confounding variables or influences – for example, hunger level, temperature, health, previous experience, and personality. Although it is difficult to control for all
confounding factors in any experiment, promoting an awareness of
how these variables may affect animal behavior will highlight good
scientific practices. Third, the problem of pseudoreplication can also
be incorporated into the activity’s discussion (see below). Pseudoreplication, or incorrectly treating data points as independent, has to
be properly addressed when performing statistical tests and has been
a point of concern among scientists (Hurlbert, 1984). Therefore, it is
important that students are familiar with pseudoreplication and its
Finally, the analysis of circular data will both complement existing and introduce new statistical principles. This exercise is designed
to be completed within a single lab period (~2 hours) and is ideal for
students ranging from high school to undergraduate levels. For high
school instructors, relevant Next Generation Science Standards (NGSS)
and AP Biology and Physics 2 topics are described in Tables 1 and 2.
A detailed description of the procedures and tutorials can also be
found in the Online Materials (see below).
See Table 3 for a list of materials. These are listed per group, two to
four students per group being optimal.
Pill bugs (Armadillidium spp.), also known as woodlice, sow bugs,
potato bugs, or roly polies, are a terrestrial crustacean of the order
Isopoda. They are harmless, easily handled, and known for their
ability to roll into a ball in order to protect themselves. The common
pill bug, Armadillidium vulgare, is native to Europe but has been
introduced worldwide and is regularly found in North America.
Instructors (or students) can collect pill bugs underneath loose leaf
litter or debris on the ground, often in cool, dark places. Alterna-
tively, they are readily available for order from biological supply
companies (see Table 3). They can be kept on lightly damp soil or
paper towels in any small container at room temperature with air
circulation. Just prior to the beginning of the experiment, it is rec-
ommended to transfer each pill bug to a separate 76 × 20 mm tube
(Table 3) containing a small, damp piece of paper towel.
Depending on the time available and student background, the instructor can perform several steps to facilitate the construction of the pulse
magnetizer. We recommend having all wire leads previously stripped
of insulation and pre-connecting (preferably with solder) the push-button switch to the positive (red) terminal of the 9-volt battery
connector. Connections can also be made between two bare wires
by twisting together tightly and covering with electrical tape.
Part 1: The Mechanisms of Magnetoreception
We provided a handout (Appendix) and lecture slides (see Online
Materials) that the instructor can use to familiarize students with
the proposed mechanisms of magnetoreception. The instructor
can choose to present the material in the lecture or have the students learn independently from the handout. Comprehension
questions are provided in the handout.
Part 2: Circular vs. Linear Statistics
Because the data collected in orientation studies are often directions,
or angles, they have to be analyzed differently from traditional linear
Table 1. Next Generation Science Standards (NGSS) relevant to our lesson plan.
Scientific Practice NGSS Standard Relation to Our Lesson Plan
Planning and carrying out investigations:
Plan and conduct an investigation individually and
collaboratively to produce data to serve as the basis
for evidence and in the design of further experiments.
HS-LS1-3 Students can work together and/or independently
Analyzing and interpreting data:
to carry out an experiment, in which they build an
apparatus and collect all the data, with
opportunities to alter the experimental specifics to
answer additional questions.
Apply concepts of statistics and probability to
scientific questions and problems, using digital tools
HS-LS4-3 Students collect their own data and then analyze it
using circular statistics. Additionally, we provide
and describe online resources for using the R
coding platform during statistical analysis.
Using mathematics and computational
Use mathematical and/or computational
representations of phenomena or design solutions to
HS-LS2-1 Students are introduced to and can use circular
statistics, introducing them to likely novel ideas
that are related to more familiar statistical
measures, such as the mean.
Engaging in argument from evidence:
Evaluate the evidence behind explanations or
solutions to determine the merits of arguments.
HS-LS4-5 Students must evaluate the data that they and their
classmates collected in order to evaluate the evidence
for and against magnetoreception in pill bugs.